Many industrial applications utilize thorium-232 (Th).
Thorium-232 is an isotope of thorium with a nucleon number (mass number) of 232.
State how the composition of a nucleus of thorium-232 differs from that of a nucleus of thorium-230.
An atom of a different element also has a nucleon number of 232. State two differences between the radioactive nucleus of this atom and the nucleus of thorium-232.
Thorium-232 decays to an isotope of radium (Ra) by alpha-particle (α\alphaα-particle) emission.
Complete the equation for this decay by determining the value of the four unknown numbers A1A_1A1, Z2Z_2Z2, A3A_3A3, and Z3Z_3Z3:
90A1Th→Z2228Ra+Z3A3α {}^{A_1}_{90}\text{Th} \rightarrow {}^{228}_{Z_2}\text{Ra} + {}^{A_3}_{Z_3}\alpha 90A1Th→Z2228Ra+Z3A3αOne reason for choosing α\alphaα-emitting isotopes in certain applications is that α\alphaα-particles are highly ionizing. Explain why α\alphaα-particles are more strongly ionizing than β\betaβ-particles.
Thorium-232 has an extremely long half-life of 14 billion years. Explain the advantage of this very long half-life for its use and subsequent safe disposal.
484 exam-style questions on CIE IGCSE Physics 5.2 Radioactivity, covering 5.2.1 Background radiation and measuring count rate, 5.2.2a Alpha, beta and gamma emission, 5.2.2b Deflection and ionising effects of nuclear radiation, 5.2.3a Radioactive decay, 5.2.3b Effects of decay on the nucleus and decay equations, 5.2.4a Half-life, 5.2.4b Choosing isotopes for applications, and 5.2.5 Effects of ionising radiation and safety precautions. Each one has a worked solution and a mark scheme showing where the marks go.